| As the length and tension requirement of cable is higher and higher. Common winch faces several problems: speed accuracy is not high; no efficient way to protect the cable; the winch can not adapt for different diameter cables. To solve above problems, a solution of variable pitch cable tension-reduction hydraulic winch is proposed. The research of this paper is essential both in theory and engineering.The paper analyze the structure of the winch hydraulic system firstly, then establish the mathematical modeling of valve-controlled motor system. Based on the tribology theory, this paper puts forward a tension-reduction unit. Most tension on the cable is transferred to friction between cable and wheel, the cable will be protected well during working progress. To meet the requirement of cable with special structure, the proposals of deslick wheel and friction wheel of variable friction coefficient are mentioned. In the variable pitch cable system, PLC is the main controller and photoelectric encoder works as the speed feedback unit. Input value of PLC includes the diameter of cable and the speed of cable drum, after the calculation of PLC the power amplifier will get a corresponding output which can control the rotary speed of the cable lead screw. Speed of the motor which drive cable lead screw will be changed when diameter of cable is modified. The winch of this paper can adapt to different diameter cables. During the algorithm research progress, introduce an efficient way to calculate the parameter of the pseudo feedback controller. To solve override problem of the last stage energy provide unit, the anti-saturation integrator is applied.Based on the theory researched in this paper, the experiment models of winch speed control system and variable pitch cable system are designed. Both theoretic and experimental research demonstrate following conclusions. The winch speed control system with PDF algorithm has fast response, easy parameter adjustment, excellent disturbance-handling ability. The variable pitch cable system which driven by servo motor can follow the rotation of cable drum strictly and meet the requirement of different diameter cables. |
